You’ve likely observed the impact on your day when you miss the recommended 7 hours of sleep. You might not be as alert or may feel more irritable. A lack of sleep can manifest as forgetfulness or a lack of motivation for daily activities. Additionally, insufficient sleep can weaken your immune system, increasing susceptibility to colds or flu.
Just as your body requires rest, your brain also needs downtime to recover from daily activities. Without regular, sufficient sleep during midlife, you could be increasing your risk of dementia. A 2021 study published in Nature Communications tracked nearly 8,000 individuals from midlife over 25 years. Those who slept less than 6 hours in midlife had a 22% to 37% higher risk of dementia compared to those who got at least 7 hours.
Without enough sleep, your brain misses the chance to clear out substances like beta-amyloid proteins that accumulate throughout the day. According to Harvard Medical School, some researchers suggest that beta-amyloid proteins may clump together, forming plaques that can lead to dementia types like Alzheimer’s. One sleep stage is crucial for removing brain waste.
How deep sleep clears the brain
During sleep, your brain activates its cleanup system to eliminate waste. Similar to how the lymphatic system removes toxins from the body, the brain utilizes the glymphatic system to flush out potentially toxic substances. This system operates most effectively during deep sleep, or slow-wave sleep. At this stage, brain cells slightly contract, allowing more space for fluid to flow and remove waste from the brain.
As reported in a 2020 article in Brain Sciences, issues with the glymphatic system may be linked to neurodegenerative diseases like dementia. People with Alzheimer’s often experience sleep disturbances, though it’s unclear if poor sleep contributes to the disease or serves as an early warning sign.
With age, the glymphatic system’s efficiency naturally decreases. One reason is reduced production of water channel proteins known as AQP4, which regulate fluid flow between brain cells and cerebrospinal fluid. Other age-related changes, like weaker blood vessel pulsations and shallower sleep breathing, also slow glymphatic function. In Alzheimer’s, AQP4 channels are often reduced or misplaced, hindering the brain’s ability to clear out beta-amyloid proteins, which then accumulate and speed up brain damage.
Improving your glymphatic system and sleep
The 2020 article in Brain Sciences suggests several lifestyle changes that can enhance glymphatic system efficiency. Omega-3 fatty acids, for instance, may support glymphatic function by reducing inflammation and ensuring proper AQP4 channel placement in the brain. Periodic fasting can also improve AQP4 channel placement by boosting a compound that regulates genes linked to glymphatic health.
Although most people change positions during sleep, lying more on your right side may enhance glymphatic clearance (note that sleeping on your back is linked to higher dementia risk). Heavy alcohol consumption and chronic stress can impair the system, whereas regular exercise aids in waste removal from the brain and guards against age-related cognitive decline.
Dementia risk isn’t solely tied to glymphatic function and deep sleep. A 2017 study in Neurology indicated that REM sleep, the stage associated with most dreaming, might also be significant. Each 1% decrease in REM sleep was linked to a 9% higher dementia risk. Improving REM and deep sleep often involves similar lifestyle habits that support glymphatic health, such as stress management and limiting alcohol consumption.
According to Harvard Medical School, excessive caffeine intake can disrupt REM sleep. Conversely, regular exercise may enhance deep sleep while slightly reducing REM sleep. Improving overall sleep quality involves maintaining a consistent sleep schedule and adopting a calming bedtime routine (here are some tricks to try if you have trouble falling asleep at night).
